Move unittests to subdir unit

Initial migration of tests from tempest.
See mail
http://lists.openstack.org/pipermail/openstack-dev/2015-February/056916.html

Partial-Bug: #1446442
Change-Id: I75daa23f4710ea557dec92f6ee24231430356127

heatclient/tests/unit/test_common_http.py

@@ -21,8 +21,8 @@ import testtools
 
 from heatclient.common import http
 from heatclient import exc
-from heatclient.tests import fakes
-from heatclient.tests import test_shell
+from heatclient.tests.unit import fakes
+from heatclient.tests.unit import test_shell
 from keystoneclient.auth.identity import v2 as ks_v2_auth
 from keystoneclient import session
 from mox3 import mox

heatclient/tests/unit/test_shell.py

@@ -38,7 +38,7 @@ from heatclient.common import http
 from heatclient.common import utils
 from heatclient import exc
 import heatclient.shell
-from heatclient.tests import fakes
+from heatclient.tests.unit import fakes
 import heatclient.v1.shell
 
 load_tests = testscenarios.load_tests_apply_scenarios